git-subtree split O(N)

I'm using git-subtree split to extract changes to a directory previously added with git-subtree add, in my local repository. The split is going into its own branch, which I then push to the upstream.

The problem is that every time I split, git-subtree starts from the very beginning of the commit log and works its way forward. I thought that it was only supposed to do that once, and that subsequent splits would start from the last commit in the destination branch (I keep the split branch around).

What's going on?

Vinnie> I'm using git-subtree split to extract changes to a directory Vinnie> previously added with git-subtree add, in my local repository. The Vinnie> split is going into its own branch, which I then push to the upstream.

Vinnie> The problem is that every time I split, git-subtree starts from the Vinnie> very beginning of the commit log and works its way forward. I thought Vinnie> that it was only supposed to do that once, and that subsequent splits Vinnie> would start from the last commit in the destination branch (I keep the Vinnie> split branch around).

Are you using -rejoin?

I am not using --rejoin. Admittedly, the documentation is somewhat opaque on its usage:

"--rejoin:: This option is only valid for the split command."

This is confusing. One would think that an option named "rejoin" has more to do with merge or pull than split. Although I guess the meaning is that you want your local changes to "rejoin" the upstream?

"...future splits can search only the part of history that has been added since the most recent --rejoin."

This sounds exactly like my use-case, I want to avoid starting from initial commit on a split, but...

"If you do all your merges with '--squash', don't use '--rejoin' when you split, because you don't want the subproject's history to be part of your project anyway."

I always use --squash with git-subtree pull, so I interpreted this to mean I should never use --rejoin.

"Unfortunately, using this option results in 'git log' showing an extra copy of every new commit that was created"

This is what discouraged me from ever touching "--rejoin"

I hope this helps

Thanks

Vinnie Falco <vinnie.falco@gmail.com> writes:

This is an area I want to improve.

You have to use --rejoin so subtree will remember where you left off last time. I also always specify a branch name, like this:

git subtree split -P subproj --rejoin --branch=subproj-to-push

I think --rejoin should probably be default but I need to understand the code better to make sure.

HTH.

                              -Dave